Vibrational Raman spectroscopic transitions are used to probe the dynamical processes involved in lipid-lipid and lipid-protein interactions in both real and model membrane bilayer systems. As an example, temperature profiles for intact membranes of Acholeplasma laidlawii were compared to profiles representative of bilayers formed from the lipid extract of the organism. Specific information on the effect of the physical state of the membrane lipids upon the phase transition and the organization of intramembrane components was obtained. For interpreting the Raman and infrared spectra of bilayer assemblies, extensive sets of vibrational assignments were made for model systems composed of selected lipid, carboxylic acid and alkane aggregates.